blk-iocost: grab ioc->lock for debt handling

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Currently, debt handling requires only iocg->waitq.lock. In the future, we
want to adjust and propagate inuse changes depending on debt status. Let's
grab ioc->lock in debt handling paths in preparation.

* Because ioc->lock nests outside iocg->waitq.lock, the decision to grab
  ioc->lock needs to be made before entering the critical sections.

* Add and use iocg_[un]lock() which handles the conditional double locking.

* Add @pay_debt to iocg_kick_waitq() so that debt payment happens only when
  the caller grabbed both locks.

This patch is prepatory and the comments contain references to future
changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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Tejun Heo 2020-09-01 14:52:42 -04:00 • committed by Jens Axboe

parent 7ca5b2e60b

commit da437b95db

1 changed files with 73 additions and 19 deletions

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block/blk-iocost.c

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